Process for interfacial adhesion in laminate structures through patterned roughing of a surface

ABSTRACT

The present invention relates to a process for improved interfacial adhesion of dielectrics using patterned roughing. Improved adhesion strength between layers and substrates can be achieved through increasing the roughness of the interface between the materials. Roughness may including any disturbance of an otherwise generally smooth surface, such as grooves, indents, holes, trenches, and/or the like. Roughing on the interface may be achieved by depositing a material on a surface of the substrate to act as a mask and then using an etching process to induce the roughness. The material, acting as a mask, allows etching to occur on a fine, or sub-miniature, scale below the Scale achieved with a conventional photo mask and lithography to achieve the required pattern roughing. Another material is then deposited on the roughened surface of the substrate, filling in the roughing and adhering to the substrate.

BACKGROUND OF INVENTION

The invention relates to a system and process for interfacial adhesionand, more particularly, to a system and process for improved interfacialadhesion of dielectrics using patterned roughing.

Laminate structures are used in a number of applications in the field ofelectronics. In semiconductor chips, integrated chips and variouselectric devices, such as capacitors, inductors, and resistors,materials are applied to one another in layers, thereby creatinglaminate structures. To maintain the integrity of the chips and devices,and ensure their reliability, it is generally necessary for the layersto adhere to each other. However, due to desired electrical propertiesand capabilities, it may be necessary to create a laminate structurewhere two adjacent layers are formed of materials that have pooradherence properties relative to each other. This may lead todifficulties in creating a chip or device that has the necessaryelectrical properties while still maintaining integrity and reliability.

Dielectric materials having a low dielectric constant, based on thecomposition of the material(s) used, often have poor interface adhesionto other materials used in the same device. This poor interface adhesioncan lead to decreased reliability of a device, as materials canseparate, slip and/or delaminate, thereby causing faults and failures.Moreover, poor interfacial adhesion may be found in other materials thatare adhered in a semiconductor chip level environment.

Various attempts have been made to improve interface adhesion toeliminate the effects of dicing. The dicing process may introduce flawsat the edge of a semiconductor device or chip. Such flaws can actuallyinitiate delaminating at the dielectric/capacitor interface or at otherinterfaces. Additional stresses during packaging can propagate thedelaminating into active areas of the semiconductor chip, therebycausing degradation and failure.

Interlocking structures currently exist, such as metal interconnectingand interlocking structures. Examples of such structures include Intel®“button” connectors. However, such metal interconnecting andinterlocking structures require the introduction of a specific metallayer to the semiconductor device. A metal layer may not be desirable,based on the type of chip or device being fabricated, or the propertiesand electrical capabilities desired in the chip or device. Further, ametal layer may actually prevent the realization of the very propertiesand electrical capabilities for which the chip or device is beingfabricated.

SUMMARY OF INVENTION

In a first aspect of the invention, a process for joining a firstsurface of a substrate to a second surface of a material comprisesproviding the substrate having the first surface, creating a roughing onthe first surface of the substrate, and depositing the material havingthe second surface on the first surface of the substrate such that thesecond surface of the material is joined to the first surface of thesubstrate, where the deposited material fills in the roughing.

In yet another aspect of the invention, a structure having improvedinterfacial adhesion between a first and a second substrate comprises afirst substrate having a first surface which has been roughened andresults in a roughing on the first surface, and a second substratehaving a second surface, where the second surface of the secondsubstrate is joined to the first surface of the first substrate suchthat second substrate fills in the roughing of the first surface.

In another aspect of the invention, a process for joining a firstsubstrate, a layer, and a second substrate comprises providing the firstsubstrate having a first surface, depositing the layer on the firstsurface of the first substrate, perforating the layer with a pluralityof holes such that the first surface of the first substrate isaccessible through at least one of the holes in the layer, anddepositing the second substrate having a second surface on theperforated capping layer, such that the second surface of the secondsubstrate is joined to the first surface of the substrate, and thedeposited second substrate fills in the holes of the layer.

BRIEF DESCRIPTION OF DRAWINGS

The above and other features and advantages of the invention will becomemore apparent to those of ordinary skill in the art by describing indetail exemplary embodiments thereof with reference to the attacheddrawings in which:

FIG. 1 illustrates a process for etching a surface of a substrate forpattern roughing according to an exemplary embodiment of the invention;

FIG. 2 illustrates two substrates adhered through pattern roughingaccording to an exemplary embodiment of the invention;

FIG. 3 illustrates two substrates and a layer adhered through patternroughing according to another exemplary embodiment of the invention;

FIG. 4 illustrates two substrates and a layer adhered through patternroughing according to another exemplary embodiment of the invention;

FIG. 5 illustrates a layer within a substrate adhered through patternroughing according to another exemplary embodiment of the invention; and

FIG. 6 illustrates pattern roughing according to another exemplaryembodiment of the invention.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. This invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, like numbers refer to like elements throughout thespecification.

According to an embodiment of the invention, improving the adhesionstrength between substrates in an integrated circuit or electricaldevice can be achieved through increasing the roughness of the interfacebetween the materials. Roughness may include any disturbance of anotherwise generally smooth surface, such as grooves, indents, holes,trenches, or the like. The surface interface, such as a surfaceinterface of substrates used in an integrated circuit, a semiconductorchip, an electrical component (e.g., a capacitor, an inductor, etc.) orthe like, may be roughened at a scale that is much finer than the scaleof interconnects, such as metal connectors and the like. Thus, byroughening at a finer scale, the adhesion strength may be improvedwithout substantially altering the fabrication process or the structureof the substrate. This etching results in sub-miniature featureroughness at the interface of a substrate.

A process for this roughing may include depositing the substrate thatrequires adhesion to another material and inducing the roughness.Patterned roughness of the interface may be achieved by depositing amaterial on a surface of the substrate to act as a mask and then using aetching process to induce the roughness. The material, acting as a mask,allows etching to occur on a fine, or sub-miniature, scale to achievethe required pattern roughing. Such an etching process may use a mask ata fine scale, thereby resulting in fine scale roughing of the surface ofthe substrate. Another material is then deposited on the roughenedsurface of the substrate, filling in the roughing and adhering to thesubstrate. Exemplary embodiments of the present invention will now bedescribed in greater detail below.

FIG. 1 illustrates a process for etching a surface of a substrate forpattern roughing according to an exemplary embodiment of the invention.A substrate 100 is provided. According to an embodiment of theinvention, substrate 100 may be a dielectric material. However, it isunderstood that substrate 100 may be other materials.

FIG. 1 further shows a mask 200 placed on the substrate 100. In theexemplary embodiment of FIG. 1, mask 200 is a photo mask formed from aphase separating polymer which is called a block copolymer mask. Such amask can be created by phase separating in a very uniform way to producea columnar arrangement of two phases, where one phase can be easilyetched out, thereby leaving a mask of a very fine scale that is uniform.This mask is then exposed to a lithographic process 300 to pattern roughthe substrate 100.

For example, a thin film of a block copolymer is spun onto substrate100. The copolymer film is annealed at a sufficient temperature tofacilitate micro phase separation of the blocks and to causeself-organization, such as into a hexagonal array. The film is thenexposed to a photolithographic process, such as ultraviolet light, tocreate the fine scale mask by removing one phase of the copolymer andleaving the other as a mask. The substrate 100 is then etched, such asvia a photolithographic method 300, to pattern rough the surface ofsubstrate 100. The use of block copolymers for etching is well known inthe art. However, for the sake of completeness, a more detaileddiscussion of etching using a block copolymer is described in Black, C.T. et al., “Integration of Self-Assembled diblock copolymers forsemiconductor fabrication,” Applied Physics Letters, Vol. 79, No. 3, (16Jul. 2001), the contents of which are incorporated herein by referencein their entirety.

This pattern roughness may be grooves, trenches, holes, indents, and thelike, or some combination thereof, depicted as reference numeral 150 ofFIG. 2. It should be understood, though, that any roughnessconfiguration may be etched on the substrate. In one exemplaryconfiguration, the roughness is etched in a regular hexagonal pattern,at a depth of about 200 Å.

After the substrate 100 is patterned roughened using the mask andetching, the mask is removed. Removal of the mask may be achieved by anyknow manner, and the specific process used will generally depend on thetype of mask and substrate 100 used. Once the surface of the substratehas been roughened, it can be used by depositing a material, such asanother dielectric, on top of the substrate, where it will then fill inthe roughness. This forms the micro roughened interface that willprovide the increased adhesion.

FIG. 2 illustrates two surfaces adhered through pattern roughingaccording to an exemplary embodiment of the invention. A material 400 isdeposited on the surface of substrate 100, where the material 400 fillsin the patterned roughing on the surface of the substrate 100. That is,material 400 fills in the indents, holes, grooves, trenches, etc.,generally depicted as reference numeral 150, and is formed by theprocess described with reference to FIG. 1, i.e., formed on the surfaceof substrate 100 by the etching process. According to an embodiment ofthe invention, filling in the indents, holes, grooves, trenches, etc.,may include material 400 filling substantially all of the space withinthe indents, holes, grooves, trenches, etc., such that, for purposes ofdetermining the properties of the resulting integrated circuit, theindents, holes, grooves, trenches, etc., may be treated as not existing.

Thus, the adhesion is improved between the first surface of thesubstrate 100 and the second surface of the material 400 due to theincreased interface area and patterning formed by the roughness. Thesecond surface of the material 400 may be complimentary in nature to theroughened surface of substrate 100, such that the two surfacesinterleave and provide an adhered interface. This interleaving may occurdue to the complimentary surface of the material 400 acts to fill in theetched surface of substrate 100, as described above. This process may beused for any structure where it is desirable to improve the interfacialadhesion between the substrate 100 and the material 400. For example,substrate 100 and material 400 both may be dielectric materials thathave poor interfacial adhesion properties. In such an example, theprocess of the invention may be used to improve the interface adhesion,thereby reducing delamination and subsequent failure of the chip ordevice.

Although the example of FIGS. 1 and 2 above is described with referenceto a photo mask using a block copolymer, it is understood that the maskmay be any type of mask, such as a photo mask, a heat mask, or achemical mask. According to an embodiment of the invention, mask 200 isa fine scale mask that enables the creation of fine scale patternedroughing. Other examples of masks that could be used include metaldeposition to form islands, photo-resist layers with porogen, spin onfilm with metal particles and annealed metal film. Each of these willnow be described in greater detail.

According to an embodiment of the invention, metal deposition could beused to form islands that act as a mask. By way of example, a watersoluble metal, such as Sn or In, may be applied to the substrate 100.Post annealing may then be used to agglomerate metal from the continuousfilm and form islands on the surface of substrate 100. The etchingprocess may then be performed, with the islands acting as the mask. Theislands may then be removed, and the material 400 may be deposited onthe substrate 100. While this embodiment is described with respect to awater soluble metal, it is understood that other metals that react toannealing in such a manner may also be used.

Alternatively, a photo-resist film with a porogen may be applied to thesubstrate 100. By applying heat, such as through annealing, the porogenmay be burned out or decompose, thereby creating a mask with holes. Sucha mask may then be used with etching to form a pattern roughing on thesubstrate 100. The mask may then be removed, and the material 400 may bedeposited on the substrate 100.

A further exemplary embodiment involves using film that is filled withfine metal particles. The film is spun onto the substrate 100, and thenburned off, leaving the metal particles behind on the surface of thesubstrate 100. These particles may then be used as a mask for etching toform a pattern roughing on the substrate 100. The mask may then beremoved, and the material 400 may be deposited on the substrate 100. Allof the above examples may be represented by the example shown in FIG. 1.

FIG. 3 illustrates two surfaces and a layer adhered through patternroughing according to another exemplary embodiment of the invention. Inthe exemplary embodiment illustrated in FIG. 3, a layer 500 a isprovided on the substrate 100. Layer 500 a may be a capping layer orother type of layer. Holes 502 are then formed by perforating the layer500 a. For example, holes 502 may be formed in layer 500 a by using amask, such as with a mask and etching process described above. Holes 502perforate the layer 500 a, where some or all of the holes 502 penetratethrough layer 500 a to substrate 100. The depth of the holes may rangebetween about 5 Å and about 1,000 Å, and more specifically between about50 Å to about 300 Å. However, in some embodiments of the invention, someor all of the holes 502 may perforate layer 500 a but not penetratethrough to substrate 100. This may occur, for example, where theadhesions properties of substrate 100 and layer 500 a are sufficient,but the adhesion properties between layer 500 a and material 400 are notsufficient, and thus improved interface adhesion is required.

Material 400 is then deposited on the layer 500 a. Material 400 fills inthe holes 502, thereby improving the interface adhesion with bothsubstrate 100 and layer 500 a. According to an embodiment of theinvention, filling in the holes 502 may include material 400 fillingsubstantially all of the spaces within the holes 502 such that, forpurposes of determining the properties of the resulting integratedcircuit, the holes 502 may be treated as not existing. While thisembodiment describes holes 502 in layer 500 a, it is understood thatgrooves, trenches, indents and the like may also be present.

According to an embodiment of the invention, it may be desirable to havea structure with a thin layer on top of the first substrate. By way ofexample only, a very thin layer or film of a dielectric may be placed ontop of a first dielectric substrate. This film is deposited in a thinlayer at a range of 5 Å to about 1,000 Å, and more specifically at about50 Å to about 300 Å, and may be performed for various reasons. This thinlayer may act as a capping layer. A photo etching of the film occurs,such as with a photo etching mask, where the film is perforated. Thatis, the photo etching process perforates the capping layer to create thepattern roughing.

A layer of a second material, such as the second dielectric, is appliedand that fills the holes created by the perforation in the layer. Theadhesion of the structure is governed not by the adhesion to the cappinglayer, which might be very weak, but by the regions where the firstmaterial is attached to the second material. For example, where acapping layer is located between a first and second dielectric material,there is an improved adhesion for the structure which can lessen oravoid problems where the adhesion to the capping layer might be ratherpoor. In addition, this may improve the adhesion of the second materialto the capping layer as well, such that the integrity of the whole stackor structure may be improved. This process and structure is alsorepresented by FIG. 3, for example.

FIG. 4 illustrates two surfaces and a layer adhered through patternroughing according to a further exemplary embodiment of the invention.In the exemplary embodiment disclosed in FIG. 4, a thin layer 500 b,such as a porous film, is deposited on the substrate 100. This layer maybe a separate material, such as a capping layer, or may be of the samematerial as the substrate 100. The porous film 500 b may have a numberof holes 504 within the film, in which some or all penetrate through tothe substrate 100. As illustrated in the example of FIG. 4, the holesmay be irregularly or randomly spaced within the porous film 500 b.Holes 504 perforate the layer 500 b, where some or all of the holes 504penetrate through layer 500 b to substrate 100. However, someembodiments of the invention, some or all holes 504 may perforate layer500 b but not penetrate through to substrate 100. Again, this may occur,for example, where the adhesions properties of substrate 100 and layer500 b are sufficient, but the adhesion properties between layer 500 band material 400 are not sufficient, and thus improved interfaceadhesion is required. The depth of this layer may be between about 5 Åand about 1,000 Å, and more specifically about 50 Å to about 300 Å, andthe depth of the holes may range from about 5 Å to about 1,000 Å, andmore specifically about 50 Å to about 300 Å.

Material 400 is deposited on the thin layer 500 b. Material 400 fills inthe holes 504, thereby improving the interface adhesion with both thesubstrate 100 and layer 500 b. According to an embodiment of theinvention, filling in the holes 504 may include material 400 fillingsubstantially all of the space within the holes 504 such that, forpurposes of determining the properties of the resulting integratedcircuit, the holes 504 may be treated as not existing. While thisembodiment describes holes 504 in layer 500 b, it is understood thatgrooves, trenches, indents and the like may also be present.

Alternatively, thin layer 500 b may be material with a porogen. Byapplying heat, the porogen may be burned out, leaving a thin film 500 bwith a number of holes 504, in which none, some or all penetrate throughto the substrate 100. As before, material 400 is deposited on the thinlayer 500 b. Material 400 fills in the holes 504, thereby improving theinterface adhesion with both the substrate 100 and capping layer 500 a.Again, filling in the holes 504 may include material 400 fillingsubstantially all of the space within the holes such that, for purposesof determining the properties of the resulting integrated circuit, theholes 504 may be treated as not existing. While this embodimentdescribes holes 504 in layer 500 b, it is understood that grooves,trenches, indents and the like may also be present.

FIG. 5 illustrates a layer within a substrate adhered through patternroughing according to another exemplary embodiment of the invention. Inthe example illustrated in FIG. 5, a substrate 100 has a thin film layer500 c deposited thereon. While thin film layer 500 c has beenillustrated as a porous film, such as that found in the exemplaryembodiment described in FIG. 3 above, it is understood that other typesof thin film layers, including that described in the exemplaryembodiment of the FIG. 4, may also be used.

The porous film 500 c may have a number of holes 506 within the film, inwhich none, some or all penetrate through to the substrate 100.Additional material of the same type as the substrate 100 is depositedon the thin layer 500 c. This material 100 fills in the holes 506,thereby improving the interface adhesion within the substrate 100 andthe thin layer 500 c. According to an embodiment of the invention,filling in the holes 506 may include material 100 filling substantiallyall of the space within the holes 506 such that, for purposes ofdetermining the properties of the resulting integrated circuit, theholes 506 may be treated as not existing. While this embodimentdescribes holes 506 in layer 500 c, it is understood that grooves,trenches, indents and the like may also be present.

FIG. 6 illustrates pattern roughing according to another exemplaryembodiment of the invention. According to an embodiment of theinvention, a multilayer structure may be created, where a firstsubstrate 600 and a second substrate 700 are alternately stacked, wherethe first substrate 600 and the second substrate 700 are of differentphases. That is, a very finely spaced multilayer structure is createdwhere there is one phase, e.g., one layer that is easily etched, such assubstrate 700, and there is another phase, e.g., another layer that isresistant to etching, such as substrate 600. The resulting trench-likestructure is accessed and exposed to an etching process, such as anetching chemical, to remove some portion of the layer susceptible toetching (substrate 700) so that it will leave a roughness on thesidewall of the structure. A material (not shown) is deposited withinthe trench and adheres to the structure through the first substrate 600and the second substrate 700.

The invention may allow for pattern roughening of a substrate at a fineor sub-miniature scale below a scale achieved with conventional photomasks and lithography.

A further embodiment of the invention may include selectively applyingpattern roughening to specific areas of the substrate or chip, such asby using a block out mask. For example, if the middle of the substrateneeds to remain unchanged, the edge and the corners of the substrate maybe pattern roughened. Other configurations may also be used.

While the invention has been described in terms of exemplaryembodiments, those skilled in the art will recognize that the inventioncan be practiced with modifications and in the spirit and scope of theappended claims.

1. A process for joining surfaces of portions of a semiconductor device,comprising the steps of: providing a substrate composed of a firstdielectric material having a first surface; depositing a film containingmetal on the first surface; annealing the film to form metal islands onthe first surface; forming a roughing on the substrate by etching thefirst surface, wherein the metal islands act as a mask for the etching;removing the metal islands from the first surface; and depositing asecond dielectric material having a second surface on the first surfacesuch that the second surface is joined to the first surface andsubstantially fills in the roughing.
 2. The process according to claim1, where the mask is a fine scale photo mask and the etching isperformed using a lithographic process.
 3. The process according toclaim 1, wherein the metal comprises Sn or In.
 4. The process accordingto claim 1, wherein the metal comprises a water soluble metal.
 5. Theprocess according to claim 1, wherein the roughing has a depth of about200 Å.